Am^h\iis«fm"}        Action  of  Hydrogen  Peroxide.  I31 
oxide  or  acid  with  formation  of  arsenic  acid.  The  addition  of  an 
excess  of  NaOH  to  these  several  salts  caused  in  every  case  the 
liberation  of  oxygen,  and  it  is  to  be  noted  that  when  a  small 
quantity  of  NaOH  caused  the  reaction,  the  addition  of  an  excess 
notably  hastened  the  same.  It  is  doubtful  if  the  salts  only  acting 
with  the  excess  of  NaOH  really  bring  about  the  decomposition  or 
if  this  is  due  to  the  alkali  itself,  as  it  was  subsequently  proven  that 
the  alkaline  hydrates  and  carbonates  caused  the  evolution  of 
oxygen  from  the  hydrogen  peroxide. 
Stannous  chloride  develops  considerable  heat  due  to  the  oxidation 
to  stannic  chloride ;  any  excess  of  H202  then  reacts  with  SnCl4  as 
stated  above. 
Chrome- alum,  cerous  chloride,  and  manganous  sulphate,  after  some 
time  slowly  liberate  oxygen ;  the  addition  of  alkali  hastens  the 
decomposition;  with  an  excess  of  alkali,  chromic  hydrate  is  oxidized 
to  chromic  acid,  cerous  hydrate  to  yellow  eerie  oxide,  manganous 
hydrate  to  dark  brown  manganic  hydrate.  If  a  little  of  the  chromate 
solution,  obtained  as  above,  be  covered  with  ether,  then  a  drop  of 
dilute  sulphuric  acid  added  and  agitated,  the  ether  will  become 
beautifully  blue  in  color,  due  to  the  formation  and  solution  of  per- 
chromic  acid.  It  is  therefore  possible  to  successively  oxidize 
chromic  salts  to  chromic  and  perchromic  acids;  on  the  other  hand, 
a  chromate  in  acid  solution  is  reduced  to  a  chromic  salt. 
Lead  acetate  forms  after  a  few  minutes  a  whitish  turbidity,  later  a 
yellowish  white  precipitate  separates  and  the  liquid  effervesces;  the 
addition  of  a  drop  of  NaOH  causes  a  bright  red  precipitate  and 
lively  effervescence;  upon  agitation  the  color  of  the  precipitate 
changes  to  pale  yellow ;  if  an  excess  of  NaOH  be  added  there  is 
formed  a  heavy  dark  brown  precipitate,  which  after  standing  becomes 
of  a  distinct  red-brown  color  (due  to  formation  of  some  lead  dioxide). 
Auric  chloride  liberates  oxygen  while  metallic  gold  separates. 
Platinic  chloride  (commercial  solution)  liberates  oxygen,  the  solu- 
tion remaining  yellow  in  color  and  transparent ;  the  addition  of 
NaOH  causes  the  oxygen  to  be  liberated  more  rapidly,  but  also 
without  precipitation.  A  mixture  of  platinic  chloride  and  silver 
nitrate  solutions  will  only  slowly  evolve  oxygen  from  H202;  but  the 
addition  of  a  few  drops  NaOH  will  cause  immediate  reaction  with 
separation  of  metallic  silver  and  platinum. 
Silver  nitrate  with  H202  forms  a  white  precipitate  insoluble  in 
